diff --git a/CHANGELOG.md b/CHANGELOG.md
index 29e4d1a..a81e2a1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+- **Dev Mode Warning in Docker** - DEV mode startup warning now displays correctly in Docker logs
+  - Added FastAPI `@app.on_event("startup")` handler to trigger warning on API server startup
+  - Previously only appeared when running `python api/main.py` directly (not via uvicorn)
+  - Docker compose now includes `DEPLOYMENT_MODE` and `PRESERVE_DEV_DATA` environment variables
+
 ## [0.3.0] - 2025-10-31
 
 ### Added - Price Data Management & On-Demand Downloads
diff --git a/api/main.py b/api/main.py
index 5c466cf..af34dbb 100644
--- a/api/main.py
+++ b/api/main.py
@@ -136,6 +136,11 @@ def create_app(
     app.state.db_path = db_path
     app.state.config_path = config_path
 
+    @app.on_event("startup")
+    async def startup_event():
+        """Display DEV mode warning on startup if applicable"""
+        log_dev_mode_startup_warning()
+
     @app.post("/simulate/trigger", response_model=SimulateTriggerResponse, status_code=200)
     async def trigger_simulation(request: SimulateTriggerRequest):
         """
diff --git a/docker-compose.yml b/docker-compose.yml
index 761d341..f6499ef 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -10,6 +10,10 @@ services:
       - ${VOLUME_PATH:-.}/logs:/app/logs
       - ${VOLUME_PATH:-.}/configs:/app/configs
     environment:
+      # Deployment Configuration
+      - DEPLOYMENT_MODE=${DEPLOYMENT_MODE:-PROD}
+      - PRESERVE_DEV_DATA=${PRESERVE_DEV_DATA:-false}
+
       # AI Model API Configuration
       - OPENAI_API_BASE=${OPENAI_API_BASE}
       - OPENAI_API_KEY=${OPENAI_API_KEY}